Field
The present disclosure relates to a display device having an embedded touch screen and a method for detecting a touch.
Discussion of the Background
Generally, a touch screen, which is an input device added on display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED), an active matrix organic light emitting diode (AMOLED), and the like, or embedded in the display device, is a device recognizing an object such as a finger, a touch pen, or the like, contacting the touch screen as an input signal. A touch input device has been recently mounted mainly in mobile apparatuses such as a mobile phone, a personal digital assistants (PDA), a portable multimedia player (PMP), and the like, and has also been used in all industrial fields such as a navigation device, a netbook computer, a laptop computer, a digital information device, a desktop computer supplying a touch input supporting operating system, an Internet protocol television (IPTV), a state-of-the-art fighter, a tank, an armored motorcar, and the like.
A display device in which the touch screen described above is used may be divided into a touch screen add-on type display device, a touch screen on-cell type display device, and a touch screen in-cell type display device depending on a structure thereof. The touch screen add-on type display device is manufactured by individually manufacturing a display device and a touch screen and then adding the touch screen on an upper plate of the display device, has a thick thickness, and has low brightness to have low visibility. The touch screen on-cell type display device is manufactured by directly forming elements constituting a touch screen on an upper substrate of a display device (a color filter of an LCD or a sealing substrate of an OLDE), and may have a thickness reduced as compared with the touch screen add-on type display device, but may not be manufactured in an existing process of manufacturing an LCD, such that additional equipment investment is required or a manufacturing cost is increased at the time of manufacturing the touch screen on-cell type display device using an existing equipment.
On the other hand, the touch screen in-cell type display device may be manufactured without an additional investment in equipment in a process of manufacturing a display device such as an LCD, an OLED, or the like, such that a manufacturing cost is reduced, and a high performance display device manufacturing equipment may be used. Therefore, a yield is increased, such that the manufacturing cost is further reduced.
However, in the touch screen in-cell type display device according to the related art, touch sensors and sensor signals lines generate interference with driving signal lines of the display device to cause deterioration of image quality of the display device, such that the touch sensors and the sensor signal lines are viewed, and in the case in which the sensor signal lines are disconnected, performance of the touch screen is deteriorated.
In addition, in the case in which the touch screen is embedded in the LCD, when pixel electrodes or source lines or gate lines of the LCD and the touch sensors or the sensor signal lines overlap with each other in a vertical or horizontal direction, a physical parasitic capacitance is generated, and a magnitude of the parasitic capacitance is significantly large, such that due to the parasitic capacitance, touch sensitivity is deteriorated or touch signals may not be detected in an extreme case.